Platinum silicide imagers are often preferred in the manufacture of infrared imaging devices because they are reliable and relatively inexpensive to manufacture. Unfortunately, platinum silicide Schottky diodes have a very low quantum efficiency (on the order of 1%), so that it becomes necessary to use as much of the available array surface as possible for photon induced charge generation. This is known as maximizing the fill factor.
Two circumstances militate against the maximization of the fill factor: one is the need for suppressing the leakage current caused by local fields along the edges of the extremely thin Pt:Si layer of the pixel cells; the other is the space required for the readout channels which convey the charges built up in the pixel cells to the outside world. Pertinent prior art in this area of technology includes: Kosonocky, et al. U.S. Pat. No. 4,548,671 which describes a basic Pt:Si focal plane array but does not describe any of the improvements contemplated herein; Elabd et al. U.S. Pat. No. 4,638,345 which discloses the N.sup.- guard ring implant which is eliminated by one aspect of the present invention; Rode et al. U.S. Pat. No. 4,467,340 which contains a good background discussion of Schottky barrier detector array technology but relates to a hybrid multiplexing scheme not relevant to the monolithic circuit of this invention; Kosonocky et al. U.S. Pat. No. 4,040,076 which describes a charge-skimming scheme not used in the present invention; and Wei et al. U.S. Pat. No. 4,672,412 which describes an AC-coupled randomly addressable Schottky photodiode array with a high fill factor but which is considerably more noisy and less sensitive, and is inapplicable to the charge-coupled devices involved in the present invention; Tanikawa et al., "A PtS: Schottky-Barrier Area Imager with Meander-Channel CCD Readout Registers", IEEE Electron Device Letters, Vol. EDL-4, No. 3, March 1983, which describes a meander channel serving as both the vertical and horizontal readout; and Kosonocky et al., "160.times.244 Element PtS: Schottky-Barrier IR-CCD Image Sensor", IEEE Transactions on Electron Devices, Vol. ED-32, No. 8, Aug. 1985, which shows channels serving one column of cells and an N.sup.- guard ring.